Ok, I tinkered around with the Vault a bit: this is what we have if we discard all our decks (so we have 43 more cards from our decks and 9 more cards from the bonewall OE deck).
4 Flying Weapon
1 EQ
3 Maxwell's Demon
1 Deflagration
4 Rage Potion
6 Black Hole
2 Light Pillar
2 Light Pendulum
6 Crusader
6 Sanctuary
1 Purify
3 Emerald Pillar
6 Life Pendulum
3 Emerald Dragon
5 Thorn Carapace
2 Emerald Shield
3 Adrenaline
3 Mitosis
5 Druidic Staff
With the mandatory 24 Pillars we are at 27 + 6 (+ 4 light). We need to field four decks, and we won't field more than 4 in the rest of this War, I think. Sure, hope's a good thing, but if we really go 4-0 for a couple rounds we're going to have so many salvages and possible convertions that we can field another deck without many problems, so I think we need to aim at about 40-50 pillars / pendulums. I think we need 6 for a novabow (see below), 9-10 for a Monk deck (with the 4 light extras), 12-14 for a normal deck and about 15-18 for a stall (again, see below). Total: 42-48. We need to keep or convert 10-15 more pillars or pendulums, which is quite frankly easy. If we lose we discard 24 cards, so it's pretty easy to just kill a deck since we won't have to field it anymore, so I think we're fine at keeping the exact number. We also have plenty things we can convert in our Vault, and the rest of the convertion may be used to get some Pends off of those 24 free Pillars.
The most important part this round is going to be deckbuilding. We need to come up with a plan for this and next round, and here's what I thought: if we manage to build 4 strong and original decks for this round and keep two splashes in our Vault so that the four "main" decks do different things (example: a stall, a rush, a denial and a versatile deck) and the two splashes cover the weaknesses of these same decks (I was thinking of getting Frogtal back, for one) we can play this round and if it goes well, then capitalize on our "secrets" to counterpick our opponents next round. Did I make myself clear or am I way off? x)
Anyway, here's what I think we can build with the current restrictions on the event card (I'd love to see what you think too as we're practically rebuilding the whole Vault... or what's left of it. We need to take only Life creatures as we're running short, but we can keep them from last round's. We'll need some more Adrenaline possibly but we can take Permanents and Spells mostly from other elements I think):
1) Firestall (keep most of it from last round and use up some Permanents for Fahrenheits)
2) Monk (keep it)
3) Discord Novabow (keep Novas and a Discord, use the leftovers of the Event Bonus + leftovers from our Vault to build it)
4) Air Duo (Owl's Eye, maybe Wings, Shockwaves, Thorn... The choice is the Air Duo because we can salvage most of it and we can add Adrenastaves - trials deck. Wings can be a killer if it's unexpected, especially coupled with heavy CC and healing. More offense can be added with some Adrenalines if needed. Not really unexpected if our opponents think this through, but...)
Roughly:
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5bs 5bs 5bs 5bs 5bt 5bt 5bt 5c3 5c3 5c9 5de 5de 5de 5de 5de 5de 5de 5de 5de 5de 5oi 5oi 5oi 5ol 5ol 5oo 5oo 5oo 7n5 7n5 7n5 8pr
with Frogtal and/or TwinDragons as a backup in our Vault (keep some Dim Shields, take Fractals, maybe TU). Maybe even another RT splash (3 RTs, 2 Eternities).
I'll work on the exact numbers, but I think this way we'll have a creatureless deck, two stalls and two rushes, a fractal or TU deck, a denial deck, healing decks... It's a varied mini-Vault, weakness to RT is somewhat compensated by the threat of Frogtal and Firestall, weakness to Wings is compensated by Firestall, Air Duo and eventually Twin Dragons, weakness to shields is compensated by Denialbow and Firestall, weakness to CC is compensated by Firestall, Frogtal and Air Duo.